Lump-coal or coal-briquette burning orchard heater



May 2l, 1929. `A. T. KARR LUMP COAL OR' COAL BRIQUETTE BURNING ORCHARD HEATER Filed Feb. 18. 1926 INVENTOR fri/ffii xfa/f' ATTORNEY Patentedv May 21, 1929.

ENT vvOFFICE.

ARTHUR T. KARR, OF YAXIMA, WASHINGTON.

LUMP-COAL R COAL-BRIQUETTE BURNING ORCHARD HEATER.

Application led February 1'8, 1926. SeriaLNo. 89,080.

My invention relates to a lump coal or coal briquette burning orchard heater. More particularly, my invention relates to a heater of a character suitable for use in fruit orchards to provide heat for the protection oflthe orchard againstvdamage by frost or freezing.

Serious objection obtains to the solid fuel type of orchard heater having gratos, in that the cost in the first instance is high and the care incident to operating such heaters is likewise expensive and onerous. In a small orchard of ten acres an operator may have in charge as many as five to seven hundred such heaters, and since the fuel tends to form a crust and bridge across the heater, it requires the use of a poker to break this down and as the heaters are usually in operation during the night, such attention involves the loss of much time. Some of such type of heaters have a cover as the means of regulatinr the rate of burning, but suoli are highly otbjecs tionable on account of the great amount of time required to operate.

The uncertainty and suddenness of a drop in temperature presents the condition to be satisfied of quickness of attaining effective heating combustion after lighting, particularly when the sap in the trees is running. A fewminutes of exposure may cause injury to, or loss, of the the crop for that year, amounting to thousands of dollars. The coldest part of the night ordinarily comes just before sunrise, and it is common practice then to have a force of operators on hand who are constantly watching the temperature, and upon a fall of the same below the safety point, their duty is to proceed in great haste to light the heaters throughout the orchard, which may often involve a number of acres and therefore many hundreds of heaters, and effective heat must be immediately forthcoming. Since only a small drop below the critical temperature is sufficient to do serious damage, Weather reports cannot be relied upon.

Y The period during which the heater must continue in operation is generally from one to live hours or more, and hence the heaters must be so designed that the rate of burning of the fuel may be carefully regulated. Me-

chanical devices, such as drafts or dampers,

are not practicable, and the regulation of the burnin@ should be automatic.

The heat must not be intense in the heater, as the same is most economically constructed of sheet metal and a high temperature obviously would quickly burn out such metal, and the fruit itself requires a uniform temperature. Any great heat at `one point would tend to overheat the orchard in that immediate locality, and hence small fires, properly spaced, are a fundamental requisite. The

number per acre cannot be much less than approximately forty, for otherwise the `fires would be too big and too far apart. Hence this imposes the condition for a large number of heaters, and hence the manual attention to each must be reduced to a minimum for a successfully operating orchard heater.

To provide convenience of operation, a solid fuel heater suitable for use in the orchard should be capable of being lighted from the top, so that a large hole is provided as against a small opening in the base or side, since the lighting of the heater is usually done in the darkness of the night.

There are certain proportion limitations also Which apply to a heater of the character involved. The fuel charge must be of the right shape to permit its burning at the proper rate, that is, it must be relatively/long, rather .than spread out. The proportions which I'have found to be satisfactory are: In a heater of thirty inches height, the diameter sould be about ten and one-quarter inches at the base. Experience has proven that the fuel charge, ordinarily of a quantity to run the heater for three hours, is properly disposed in such a proportionedheater to work most efficiently. The coal briquettes herein considered, which are those in common use for general heating on the Pacific Coast, for

Aabout forty percent of theirburning period supply a preponderance of volatile fuel, and for the remainder of their burning period the combustion assumes'more and more the form of incandescent glowing coke in a condensed and compact body, so that the. thin metal is heated to a cherry-red. The proportions indicated provide a heaterwhieh eilisol cieiitly 'consumes fuel having the characteris- Furthermore, a condition Which must be tics of the briquette just set forth.

y, A primary object of my invention is to provide an Vorchard heater Which satisfies each and all of said conditions, and which is open'throughout from end to end, i. e., is free of all obstruetionsof the character of grates, covers, supporting legsV and kindling brackets, and in Which the rate of burning is automatic-ally controlled at the time of VVcharging the heater, so that a heater is provided free of all mechanical devices such as drafts and dainpers for regulating the rate of burning.

. For the combustion of solid fuel, air must he admitted below the burning fuel toV generate gases, and then air must also be admitted above the burning fuel to complete the com! bustion of the gases.

Thev eflieiency of the heater dependsupon the proper balance of these two factors, that is, the admission of air to the fuel chamber, and the admission of air to the' gas combustion chamber. On the one hand, the admission of too much air to the combustion chamber must be avoided to pre- :rent the cooling of the. heated gases which are of a combustion temperature and only need a little more oxygen to vcomplete their oxid atioinand yet the admission of such air must be sufficient to complete said oxidation Vof the gases g'eiierated. The prevailing idea at `'one time was that smoke Was desirable, but

the bulletins of the Department of Agriculture, together with other authorities, all agree that heat is to be desired rather than smoke. In fact, the chief item of cost of expensive heaters pertains primarily to the smoke eliminating feature.l rlfhe carbon of the smoke is much more valuable in the form of heat. A

' primary object of my 'invention is to provide readily accomplished by the employment of 1 diflerent sized openings, sucha solution involves extra cost in manufacture. A primary purpose of my invention is to provide such progressive admission of the quantity of air p to the gas combustion chamber utilizing the saine size of hclethroughout Vthe stove. This progressive influx of air in part results iii my invention by reason of the ratio of constant` cross sectional area of air holesto .the progressively changing cross sectional area of the combustion chamber of the'heater due to its tapering design, being eight and onefquartei inches in diameter at top.

provided for in a large number of heaters of the character herein described, which heaters are required for use for a given short season of the year only, is the condition imposed by the necessity of their handling, transporting and storing. lVhere a single grower may have some one totivo thousand of such heaters to care for, the factor of storing, hanling and transporting to andfroin the orchard is manifestly a very important element in thecost, and particularly is this so in veivv of the small margin of profit which noW obtains in the fruit growing industry. The importance of all this is made very obvious by reference to the fact tliat'one user has actuallyfin use eighteen thousand'of the heater-semrbodying my invention of the specific design herein set forth.

A further condition to be satisfied is the refueling of the heater VWhile in operation, if the period of heating is of such duration as to require such refueling; In other Words, there must be la proper disposition of the air ports in addition to Vthe requirements for generating the gases and for the proper combustion of the gases above explained. `Smoking and siiiouldering must be eliminated in a heater to meet the required conditions, and therefore a primary purpose of my invention is to provide a heater having such disposition of air ports that the gases Will not become too cold by the time that they reach the combustion chamber, but 'will be caused to burn promptly and' thus prevent smoking and snioulderiiig.

ln connection Wit-h repeated re-fueling, it becomes necessary to clear the iire-bed of ashes. In order to provide for an even burning temperature Without attention from the operator, I provide for the fire to burn from the upper'portion of the charge downwardly. lVhile this mede of operation is advantageous to provide a uniform burning rate, when .such inode of operation is adopted with a grate in the bottom of the heater, it so happens that Vvery often there is a considerable unbuined fuel next to the grate, which affords a serious obstruction to the removal of the ashes formed thereabove, i. e., such unburned coal is of a size `which Will not pass through the grate openings, and it is difficult therefore to get the ashes to pass on through. Such unburned fuel iay have already reached the eokiiig stage When it is more or less impervious to the ashes. A primary purpose of my invention is to provide for the elimination of the ashes and yet retain the unburned fuelE for fuel purposes for continued burning. Y

The above mentioned general objects of my invention, together with others inherent in the saine, are attained by the device illustrated in the following drawings, the same being merely preferred exemplary forms of embodiment of my invention, throughout which drawings like reference numerals indicate like parts: t

, Figure 1 is a view in perspective of an orchard heater embodying my invention;

Fig. 2 is a view in longitudinal section of a heater embodying my invention, the front half being removed to show the disposition of the fuel and kindling within and the space left for the gas combustion chamber; and

Fig. 3 is a plan view of the metal blank employed to constructthe heater embodying my invention.

The body 4 of the heater embodying my invention is constructed of thin sheet vmetal, ordinarily 24 to 26 gauge. The requirement of cheapness and inexpensiveness of manufacture generally limits the construction material fora heat-er of the character described to such metal. This limitation is particularly important since the device must have a form and proportion which will provide for the proper combustion of' the fuel through its varying stages, i. e., while the fuel is giving off the volatile gas portion of vits fuel properties as well as when it is burning as coke,

because if the heat is too great duringvthe cok'- ing stage, or any other stage, it is manifest that the metal will be burned out.

That portion of the heater embraced Within the portion indicated at 5 represents the fuel chamber in the heater embodying my invention. The portion thereabove, and designated by the numeral 6, represents the gas combustion chamber. For the admission of air below the burning fuel, I provide eight draft holes 7, 8, 9, 10, 11, 12, 13 and 14 on the level A. Other holes are disposed on the following levels and in numbers as follows: On level B four holes, namely, 15, 16, 17 and 18; on level C, one hole 19; on level D, one hole 20; onlevel E two holes 2l and 22;- on level F, three holes 23, 24 and 25; and on level G, three holes, 26, 27 and 28.

The approximate location of these various levels may be as follows: Level A is approximately two inches above the bottom edge of the heater; B may beapproximately six inches; C, approximately eleven and onehalf inches; D, approximately thirteen and one-half inches; E, approximately sixteen inches; F, approximately twenty-one inches; and G, approximately twenty-five inches. These proportions have been found to give very satisfactory results. A change of more than two inches, particularly in Athe lower levels of the holes, results in-arvery appreciably modified performance of the heater.

The function of the holes on level B Will be explained later. The hole on level C admits oxygen, the primary purpose of which is to start the oxidation or burning of the generated gasesto which has been imparted a combustion temperature in the fuel chamber. Only one hole is provided at this level, so that there will not be too great a cooling of these gases and, likewise, only one hole is provided on level D to carry said combustion on to a greater extent. The oxidation of the gases being thus commenced by the oxygen iniiux at C and D levels, the heat generated by said oxidation next sets fire to or oxidizes a larger quantity'of gaseous fuel, which requires a still greater influx of oxygen, when the same have reached level E, where two holes are provided. And as the gases reach level F, by the same reasoning three holes are employed. Likewise, on level G for the same reason three holes are provided. The effectiveness of the holes on levels E, F, and G, and particularly on levels F and G, is influenced by the tapering design of the heater. Manifestly, by the reduction of the cross sectional area,

the three holes on level G admit a greater ratio of oxygenthan is admittedon level F, and so on down. For the most efficient combustion of the fuel, therefore, the tapering design is highly important to provide in part for this progressive influx of oxygen; Manifestly, such progressive influx results directly by reason of the ratioof constant cross sectional area of the oxygen orair holes to the progressively decreasing cross sectional area of the combustion chamber as the gases proceed upwardly.

In the initial charging and burning of the fuel,'the four holes on the B level do not play an Aessentially important part, and for this reason, their function was omitted in the above description. However, when it becomes -necessary to re-fuel the heater to prolong the 'heating effect beyond Vthat provided for the ordinary period, then the four holes on the B level become of great importance. VFor reasons herein explained, vit is necessary to `provide prompt-ignition of the fuel in general, because the effectiveness of the heating must be immediate to provide for the sudden drop in temperature to render the heater effective in protecting the orchard. Upon refueling, it is a well known fact that the addition of new fuel tends to chill the fre and produce a smoking and smouldering condition because of such chilling. To overcome this, therefore, the four holes on the B levelare disposed to add the necessary oxygen in close proximity to the point where the new fuel will ordinarily meet the already burning charge, and thus provide the necessary oxygen to avoid said smoking and smouldering period. At least, such period is reduced to a minimum, as the heater embodying my invention has proven in experience uponre-fueling to promptly burst into flame with the addition of new fuel` so that the smoking and 'smouldering period is practically eliminated,

and the full heating effectiveness of the fuel is maintained.- If these holes, (four being found a satisfactory number), were not '1ocated on the B level, the escaping gases which may start out at a combustion temperature yPacific Northwest.

would soon become chilled by the fuel in the upper part and would escape unburned, and this would continue for some time until the heat generated would be so great that it .would cause all of said gases to burst into flame ,at theupper levels where the further admission of oxygen is provided. y p

By reference to the blank shown in Fig. 3, wherein appears the-disposition of the holes with respect to each other, it is manifest that vthey are in staggered relation, which disposition admits oxygen at the most advantageous points.- 'lhisavoids too great an influx at one point which would obviously chill the heated gases, andat the same time there must be a suflicient influx of oxygen to provide for the complete combustion of the gases as rapidly as possible, and to convert the carbon in the smoke into heat before itsescape from the top of the heater. Actual'experience establishes the fact that heaters embodying my invention are practically smokeless, a fact substantiated by a report of the United States lVeather Bureau Meteorologist.

In-tht device embodying my invention, the

length of the burning period is determined Vsuch as charcoal, coke or carbon briquettes are: highly undesirable and fail to meet the said requirement for promptness of providing heat to the endangered orchard. So complete is this failure that said fuel and the heaters designed to accommodate the saine are not used in the extensive fruit districts 'of the Heretofore, carbon briquettes or coke, which are very slow in igniting, have been the preferred type of'solid fuel for orchard yheaters inthe citrus fruit sections. Hou/ever, so desirable is the quick igniting that the heater embodying the invention herein set forth is rapidly.supplanting the other types of heaters, even in the cit-rus fruit sections. A further advantage of designing this heater to burn lmnp coal or vcoal briquettes is that this type of fuel is very cheap, abundant and widely availablea For example, carbon biiquettes cost from tgiventy to twenty-five dollars a ton, while coal briquettes, which the heater embodying my invention is designed to burn,`costonly approxiinately ten to twelve dollars per ton. Thus, a

briquettes.

composed of a fuel which is quickly rendered distinct line is to be drawn between the heater designed to use coke or carbon briquettes, and the heater designed to use lumpcoal-oi coal Thecoal vbriquettes are largely volatile and itis these volatile gases which my invention employs tov produce the quick ignif tion,-these gases alsoproviding initially an abundant heating effect for the heater until the briquette assumes the characteristic combustion of carbon or coke. That is, during the thirty to fifty ininuteperiod in which the carbon or coke is attaining an effective heat-producing condition, my invention is designed to utilize the gaseous content of the fuel to immediately render the heater inefficient heatproducer. Obviously, this results in providinfra prolongation of the effective heat-producing period. The heater embodying'my inbeing regulated as to its period and rate of burning. Coal briquettes having a uniformity of composition, size and shape, afford an excellent fuel,.and the design of my heater is especiallly adapted to take advantage of their properties. These features are the proper proportion of diameter to height of the fuel charge; the providing of a fuel chamber and a gas combustion chamber g the proper disposition of the drafts as respects the fuel chamber and the proper disposition of the air or oxygen ports as respectsV the gas combustion chamber; and also the disposition of the kindling in respect to the height of the fuel charge,V which last feature results from the method part of my invention. l have found that by changing the position, up or down, of the kindling intermediate the length of the fuel charge, l can predetermine the rate of burning in the heater of my design. To prolong the period, l place the kindling very close to the top lof the fuel charge, and know, for example, for a three-hour period, that eight briquettes should be placed above the kindling and eighteen below, amounting altogether to about sixteen pounds of fuel. To increase the rate of burning and to shorten the burning period, a larger proportion of lthe fuel should be placed above the kindling.

The heater of my design permits of the lighting' of the kindling by merely dropping some burning oil from a lighting torch, which immediately sets the fuel charge to burning. Since this lighting may be done through thelarge opening in the top of the heater,

the convenience of my design of heater is apparent, when it is remembered that the operation is done in thenight time in the dark.

My form of design of heater is frustoconical, sol that said tapering, in addition to providing for the efficient combustion of the fuel gases, as heretofore explained, also pro.- vides for the nesting of the heaters for handling, transporting and storage purposes. The bead 29 prevents the heaters Vfrom becoming wedged within each other, and insures theirready separation, even after being stored for nine months or more of the year, and when a great superimposed number 1s placed upon any given one. v

The heater embodying my invention is free of all obstructions. it is free of crates, covers, legs and internal brackets which would prevent nesting. Thus, the absence of the grate has also this advantage, as well as the advantage of permitting the elimination of the ashes when it is desired to re-fuel. lVth the heater embodying my invention it is only necessary to rock the same, and the ashesare caused to fall out around the lower edge of the base, leaving the unburned fuel intact.

My heater is, therefore, designed to overcome the difficulty incident to the cost and operation of heaters with grates and utilize the ground as a grate in the sense that it supports the fuel and permits relative movement between the fuel support and the heater, thereby permitting the removal of this crusted ash. That is, I move the heater by rocking the same instead of moving the grate. If it should become necessary to move the heater when charged, a heater embodying a grate would obviously permit its being readily carried and moved to another location.V By pro. viding my design of heater to operate with suitable coal or coal briquettes, I am able to move the same by merely slipping a shovel or fork beneath the heater to hold the fuel charged and proceed to any desired new location.

Moreover, the design of my heater further satisfies the requirement of convenience and simplicityv of operation byeliminating all mechanical devices to regulate the rate and period of burning, including re-fueling.

lVhere the weather conditions require only a relatively short period oran hour or two heating, I provide a heater of less capacity Instead of the thirty-inch length, this may be twenty-four inches, and in this design I reduce the number of holes in the gas combustion chamber and depress the holes on the other levels towards level A. Since the initial fuel charge is reduced, this smaller design constitutes a more convenient and cheaper heater, and if the two sizes are employed in the same orchard, it is very readily determined in the dark in which heater there has been provided the long period and the short period fuel charge. Naturally, where such smaller design is used, if it should develop that the buring period should be prolonged, then of course the inconvenience of more frequent re-fueling arises.

By this is meant that vThe turned edge 30 on each side of the blank permits the two to be interlocked and these overlapping edges then spot welded, riveted, center punched, or otherwise held together. The ports or holes 7 to 28 are preferably one and one-'quarter inch` in diameter.

Obviously, changes may be made in the form, dimensions and arrangement of the parts of my invention, without departing from the principle thereof, the above setting forth only preferred forms of embodiment.

The height may be varied from twenty tothirty-six inches and the diameter of the base may be varied from eight to fourteen inches. The number of one and one-quarter inch ports above level A may be varied in the thirty-inch high heater herein set forth from eight to twenty; however, any departure vfrom the number illustrated and described results in a decrease of eiciency.

I claim:

1. A lump coal or coal briquette burning orchard heater constructed of sheet metal, open and unobstructed throughout its length, the lower portion of which is used as a fuel chamber and the upper portion as a gas combustion chamber, the lower edge of said heater resting in operation directly on the ground, said fuel chamber portion having air draft ports therein, and said gas combustion chamber portion having means for the admission of air in progressive quantities thereto per unit of volume from the bottom upwardly.

2. A lump coal or coal briquette burning orchard heater of frusto-conical form constructed of sheet metal, open and unobstructed throughout its length, the lower portion of which is used as a fuel chamber and the upper portion as a gas combustion chamber, the lower edge of said heater resting in operation directly on the ground, said fuel chamber portion having air draft ports therein, and said gas combustion'chamber portion having means for the admission of air in progressive quantities thereto per unit of volume from the bottom upwardly.

3. A lump coal or coal briquette burning Vorchard heater constructed of sheet metal,

open and unobstructed throughout its length, the ratio of the base diameter to the height being substantially in the range of eight to twelve inches for the base and twenty toV thirty-two inches for the height, the lower portion of which heater is used as a fuel chamber and the upper portion as a gas combustion chamber, the lower edge of said heater resting in operation directly on the ground, said fuel chamber portion having air draft ports therein, and said gas combustion chamber portion having air ports therein.

4. A lump coal or coal briquette burning orchard heater ,constructed of sheet metal, open and unobstructed throughout its length, the height of said heater being twenty-four to thirty inches, and the base being about ten inehes in diameter, the lower portion of which having six totWelve one and one-quarter inch heater is used as a fuel chamber and the up- (llf) holes, said holes being arranged per portion as a gas combustion chamber, the progressively 4in greater numbers at different 10 lower edge of said heater resting in operalevels from the bottom up.V e Y 5 tion directly on the ground, said fuel cham- In Witness whereof, I hereunto subscribe ber portion having air draft ports therein, my name this 11th day of February, 1926. and said gas combustion chamber portion ARTHUR T. KARR. Y 

